The most expensive movie ever made can have a case for two choices.  However, whether you adjust for inflation or not, the most expensive movie ever made exceeds $300 million.  Here is some more information on the most expensive movie ever made.

The question of inflation.  There are two ways to look at the most expensive movie ever made.  Perhaps most common, and certainly most direct, is to look at the nomial cost to determine the most expensive film.  Alternatively, inflation can be introduced into the picture.  This will adjust the amount to "today's money."  In this case, inflation can switch what is labeled as the most expensive movie ever made.

"Pirates of the Caribbean - At World's End" (2007, $300 million nominal).  The third movie in the popular film series, the film had a nomial budget of $300 million, which can be increased to about $318 million with inflation.  While having mixed reviews, the budget shined through with regard to special effects and other visuals.  It grossed around $960 million worldwide.  This movie and series of movies is part of a multi-billion dollar franchise, incorporating a them park ride, novels, and video games.

"Cleopatra" (1963, $320 million adjusted).  With a nominal budget of $44 million, it increases the most expensive movie ever made if it is based on inflation.  However, the movie wasn't successful.  Despite winning four Academy Awards, it was a failure to critics.  The movie only made $26 million in the US, $57 million overall, which made this a failure financially as well.